Tire uniformity machines may be used to detect the high or low point of fundamental harmonic of radial and lateral force variations within a tire. When measuring the tire force variations, a computer analyzes the high or low point angle of the radial and lateral force variations first harmonic from an event mark (zero angle). The event mark is set on the tire spindle shaft in conjunction with a pulse generator and pulses once per revolution. After measurement is complete, the high or low point of the tire is indexed and stopped beneath a marker head. A heated marking pin is lowered against the upper side wall of the inflated tire by actuation of an air cylinder. The heated pin transfers pigment or metal foil from a tape to place a mark on the sidewalls of the tire at the high or low point.
The above described marking system is effective if a conventional marking tape is used. Such a tape has a backing membrane that faces the heated pin and a marking material that faces the tire. When actuated, the pin presses the marking material adjacent the tire surface, and the applied heat and pressure transfers the marking material to the tire. This is sufficient for when the marking material is continuous on the membrane. However, the marking material sometimes does not meet the tire manufacturing requirements. In particular, the marking material may not clearly mark the tire, or the marking material does not last long enough to convey the desired information.
In place of a continuous marking material on a membrane, decal type markers may be used. However, such decals, which are more substantive and last longer than pigment or foil type marks, also present their own particular problems. The decals may become misaligned with the striking pin as the membrane is sequenced through the marking assembly. As a result, the striking pin may not fully engage the marking decal, and as a result, only a portion of the decal is applied to the tire. Therefore, there is a need for a decal marking system to accurately coordinate the position of the decal with the marking pin so that the decal is uniformly applied to the tire.